Hello,
My understanding is that the notion of capability is equivalent to the notion of use-case: a system usage context further described by a set of interactions between the system of interest and external actors; a collaboration between the system and the actors in order to get a specific outcome.
Regarding the labelling of the capabilities, one question would be to decide on the subject of the action defined by the capability: (1) the system or (2) the actors (implicitly by using the system). Both options seem to be valid and practically in use. The first option might lead to a confusion with a system function. The second option might blur the distinction between operation capabilities and system capabilities. I reckon that some recommendations regarding the phrasing of operational/system capabilities may be useful.
Best regards
Joel